Electric telescopy



Aug. 21, 192s. 1,681,833

J. G. ALLEN ELECTRIC TELESCOPY Filed Feb. 22, 1923 2 Sheets-Sheet l TO GENERA TOR Aug. 2l, 1928.

J. G. ALLEN ELECTRIC TELESCOPY Filed Feb. 22, 1925 2 Sheets-Sheet Qa 2 7 7 I 2 M 10 n U 2 F M xH n M m u T 6 u.

Patented Aug. 21, 1928.-

UNITED STATES 1,681,833 PATENT OFFICE.'

GILLESPIE ALLEN, OF CHICAGO, ILLINOIS.

ELECTRIC TELESCOPY.

Application tiled February 2 2, 1923. Serial No. 620,555.

The object of this invention is the improv- 'ing of methods in electric telescopy, to make the same of practicalxvalue, using a novel combination of apparatus, the 'separate units of which are employed in connection with other arts.

This 'invention uses a sending station and a receiving station.. The sending station originates impulses'which are transmitted by 1u wire or wireless to thev receiving station Where they operate the receiving apparatus in such a manner as to cause an ima e of the real view to be produced. The sen ing ,station may consist of a number of units, such as hereinafter described, focused 0n the same view, or may consist of units or groups of units focused on adjoining portions of the view; each sending unit operating its corresponding receiving (or view reproducing) unit at the receiving station.

The equipment of the sending statlon 1s represented schematically in Fig. 1, While that at the receiving station is represented in Fig. 4. Figure 2 shows a characteristic curve (current against time) for current iiowing.

thru' cell 12 while apparatus is in operation.

This curve also represents the amount 0i' light entering cell 12 and the amount of light being reiected by oscillograph 13 thru lens 19 (both plotted against time). Fig. 3 represents the transmitted curve showing' the im'- pulses electromagnetically induced by change in Value of current owing thru cell12.

YThe view, which is to be transmitted, has its image projected into the optical train, by means of lenses 1 and 2, thru cylindrical lens 4 on to oscillograph mirror 5 from which it reflects', thru collimating cylindrical lens 6, on to mirror 7, which has its face slanted 45 toward lens 6. This sends light vertically down to mirror 8, which is at 45 away :from lens 9, thru which the light is now relected, converging on to oscillograph mirror 10 which reflects it thru lens 1l into cell 12. Generators, such as are used in modern telephony for the production of carrier currents, `produce alternating currents to vibrate mirrors 5 and 10 at the sending' station in exact synchronism-with mirrors 25 and 20 respectively at the receiving station. The lightentering cell 12 isfrom the entire view, but only from a small spot at any instant, the spot traveling over the view many times a second. The light intensities from different ortionsof a'vlew'var The variations Ain ight intensityof the ea-m entering cell 12 produce-variations in the resistance of the cell, which, in' turn, causes variations the .electric current flowing thru the cell. This varying current electromagnetically roduces impulses in a secondary circuit. igure 2 represents the current flowing thru the cell and Fig.v 3 represents the induced impulses in the secondary circuit. The impulses vare amplified, imposed on a high frequency wave and transmitted on this carrier wave over, wires or by wireless. In case the transmission is by wire, Ithe lines would be loaded for high frequency.' The ordinary toll lines of 'telephone systems could be used as they are so loaded.y Transmission over long distances is aided'by amplification at intermediatepoints. These impulses operate the highly damped oscillograph 13 swinging the mirror into various positions, the mirror not immediately returning to neutral position but remaining in practically the same position until acted on by the succeeding impulse. This 'action is that of the integrating galvanometer which is Well known to physicists. The alternatin currents which operate oscillographs 5 van 10 are imposed onv other frequencies and transmitted b wire or wireless, and at the receiving station they operate oscillographs 25 and 20 in synchronism with'oscillographs 5 and 10 respectively. A source of light 14 has its radiations reflected by parabolic mirror 15 thru heat lter 16 and graded translucent screen 17 This screen is nearly opaque at one edge and is less and less dense until quite translucent at the other edge. The ylight sent thru lens 19 by mirror 13, varies directly in proportion to the angle mirror 13 makes with the zero light position. The magnitude of this angle is dependent upon the summation of'impulses received and 1s directly proportional to the amount of Vlight entering the cell at the sending station. Thus the light sent thru lens 19ovaries the same as the lightentering cell '12. The beam focuses on oscillograph mirror 2O which throws it thru lens 21 into a narrow band 0n mirror 22 whence it is reflected up to mirror 23 and thru cylindrical lens 24 to oscillograph 25 which reflects'it out thruA cylindrical lens 26, concave lens 28 and convex lens29 and on to the projection screen or sensitized film 30. The true coloring ofthe view is reproduced by using several units, such as described, focused on the view and with the lenses at the receiving station focused on a common screen, light lters 3 and 27 beinginserted at sending and receiving stations respectively. Since the light filters cut out the rays except those of the desired color at the sending station, the cell can be affected by only rays of that color received from the view, and the corresponding set at the receiving station will product.` light in proportion to the light of that color eing received at the sending stay tion. Thelight from the source of illuminai0 tion 14 will be white, butlilteis 27 will allow only rays of the desired length (color), to pass to the screen 30. Three units,`one using yellow, one red and the third, blue, will blend in to all shades necessary for practical reproduction. The relation of the frequencies or the vibrating mirrors is such-that the beam or light does not travel the same path at each retracing, but is such that the close threaded grid of light moves along swiftly so that a streaked effect is prevented. The principle ol this is the same as that of two 0ear wheels, the number of teeth oit-one not being a factor of the number of the other, so that their relative positions after one revolution of 'the larger, is not the same as before that revolution,

Absolute synchronism of the corresponding oscillographs is assured (both in cycles per second and in positionv during each cycle) by using a common source of power and having the corresponding oscillographs identical in every way. The opticaltrains (object to cell 12 and image to mirror 13) are identical, thus eliminating the possibility of insucient coinpensations for diderences in apparatus Screen l7, which is quite translucent at one edge and gradually less translucent until opaque at the other edge, provides the ad- 4 vantage of allowing mirror l3 a large enough Qi-,angle to `swing thru in reproducing the light fluctuations. .lt can easily be shown 'that the `v larger this angle, the more stable becomes this part of the system.

The use of distributed loading reduces to` av minimum the effect of the reactence of thel transmission lines on different wave lengths, thus the signals are kept in their proper pro portion and sequence.

Carrier currents, such as are used in longl toll. lines in telephone systems, used in --this system for two purposes'. First; the iuctuations, produced by the actionorn the light beam on the selenium cell, induce `impulses which are imposed on a'carrier, Seo ond; two additional carriers are required, one

, for each pair of corresponding osciliographs Also other carriers are used to take care of the extra units in the case of color reproduction. It will be noted that the rotating mirrors iii this system are all vertical thus making it possible to use the type of oscillograph in common use. y

This method of transmission avoids the use of commutatore, incandescent lamps as a source of varying light, and motor drivea il commutator interposes a varying resistance which destroys the sensitiveness of a sfstem. Incandescent lamps as varying sources oil illumination are very inellicient due to the time lag of incandescence which sinoothes out the effects of changes in currentD Motor drive does not provide close enough speed regulation as .001 per cent variation is too great for any reproduction 'lhe closest approach to satisfactory speed control is obtained thru the use of synchronous motors, but the inevitable hunting (oscillation ol the rotor from the synclironousneutral position) pre vents the attainment of good results.

Vl`he method herein set forth contemplates the distant transmission'of scenes, views, photographs, documents, signatures, designs, motion pictures, and the like. ln the claims .and in this speciiication reference to the transmission or a icture or view includes all ol the above, and a so the art relating to television.

Past attempts to secure good reproduction failed mainly due to the fact that dissimilar sending and receiving apparatus was used. For example; the use of mirrorsmounted on a revolving drum at the sending station and oscillograplis at the receiving station, results in having constant angular velocity at the sending station and reversing motion with varying speed at the receiving station. (lt will' be noted thatthe optical trains at sending and receiving stations are identical lor this invention.)

TW hat l claim is 2-4 l. ln the art ol' transmitting pictures and the lilre the combinaiton of a transmission vstation including means to produce electrical impulses, a receiving station including a source of light, 'a light intensity grading screen thru which the light rays 'from the lill) ics source or light pass, a screen, and an integrating dead beat oscillograph actuated by electrical impulse from said transmitting station operably positioned between said grading screen and the second mentioned screen j ior receiving' light rays from the 'former and projecting them on the way to combination or alight source, means to transniit rays otilight from the light source including an oscillograph, and a heat lter between the light source and said oscillograph to prevent damage of said oscillograph by heat from the light source.

4. In the art of picture transmission the combination of sending and receiving stations each including optical trains with oscillographs, means synchronously operating said oscillographs of said stations, means to transmit. light controlling impulses from the sending to the receiving stations, .a light source at the receiving station, means to variably control light rays of the light source by said impulses, color filters in the, optical trains at both the sending and receiving stations, and a heat filter between the light source and the last mentioned means.

5. In the art of picture transmission the combination of a sending station including a light sensitive device, a picture, and an optical train for refiecting light from the picture to the light-sensitive device including a plurality of oscillographs having successively reduced reflecting areas from the picture 'in the direction of the light sensitive device.

6. In the art of transmitting pictures and the like the combination of a'picture, an oscillograph having a refiecting` mirror thereon, an optical train between said oscillograph and the picture for directing light from the picture to said oscillograph mirror, said optical train including a color filter, a second oscillograph, slantin mirrors between the firstl and second mentioned oscillographs for directing light rays from the first mentioned oscillograph towards the'second oscillograph, a collimatmg cylinder lens between the slanting mirrors and the first mentioned oscillograph in the path of reflected light rays, said second mentioned oscillograph having the mirror thereof positioned to reflect light rays from the slanting mirrors into the light sensitive device.

7. In the art of transmitting pictures the combination of a transmitting station having means therein for transmitting variable light rays into electric current impulses, and a receiving station comprising a source of light, an oscillograph mirror connected for operation by the impulses from the transmission station, means to direct graded light rays from the source or light to said oscillograph, a second oscillograph for the receiving station positioned to receive light rays from the first mentioned oscillograph, a third oscillograph for the receiving station, means between the second and third oscillographs for reflecting light rays from the second oscillograph onto the third mentioned oscillograph, a screen, and an optical train between the third mentioned oscillograph and screen for directing light rays from the third oscillograph, into picture forming relation on said SCIBED.

8. In the art of transmitting pictures the combination ofa transmitting station having means therein for transmitting variable light rays into electric current impulses, and a receiving station comprising a source of light, an oscillograph connected for operation by the impulses from the transmission'station, means to direct graded light rays from the source of light t'o said oscillograph, a-sccond oscillograph for the receiving station positioned to receive light rays from the first mentioned oscillograph, a third oscillograph for the receiving station, means between the second and third oscillographs for reflecting light rays from the second oscillograph onto the third mentioned oscillograph, a screen, an optical train between the third mentioned oscillograph and screen for directing light rays from the third oscillograph into picture forming relation on said screen, and a color filter in said optical train.

9. In the art of transmitting pictures and the like by wireless the combination of a transmitting station including means to produce electrical impulses, a receiving station including a source of light, 'a screen, and an integrating oscillograph actuated by electrical impulses from said transmitting station operably positioned to receive rays of light from the source of lightand project them on the way to the screen.

10. In the art ofA transmitting and receiving pictures and the like, in combination a transmission station including a picture, an oscillograph positioned to direct light rays from said picture, a second oscillograph for the transmission station adapted to receive rays of light from the first mentioned oscillograph, alight sensitive current controlling device for receiving rays of light from the second mentioned oscillograph for translating the light variations into electric current impulses, a transmission line for transmitting the current impulses, and a receiving station including a light, an integrati'n oscillograph operated by means of the electric current impulses from the receiving station, means to direct rays lof light from the light of the receiving station onto said integrating oscillograph, a'second oscillograph at the receiving station for receiving rays of light from the integrating oscillograph, a third bscillograph at the receiving station for receiving rays of light from the second oscillograph of the receiving station, a screen for the receiving station onto which the light rays are refiected from the third oscillograph of the receiving station, and means for synchronously operating the oscillographs of the transmitting station with the second and third oscillographs of the receiving station.

JAMES GILLESPIE ALLEN. 

